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United States Department of Agriculture

Agricultural Research Service

Title: Liquid-Solids Separation of Flushed Swine Manure with Pam: Effect of Wastewater Strength

Authors
item Vanotti, Matias
item Rashash, D.M.C. - NC COOPERATIVE EXT SER
item Hunt, Patrick

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 26, 2002
Publication Date: December 1, 2002
Citation: VANOTTI, M.B., RASHASH, D.M.C., HUNT, P.G. SOLID-LIQUID SEPARATION OF FLUSHED SWINE MANURE WITH PAM: EFFECT OF WASTEWATER STRENGTH. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 2002. V. 45. P. 1959-1969.

Interpretive Summary: Organic polymers are useful to increase separation of suspended solids and reduced carbon compounds from liquid swine manure. Along with the solids there is a capture of the nutrients associated with small particles typical of these wastes. The combined effect reduces the size of process units to treat the liquid, provides needed alternatives to land application, and increases the amount of materials available for value-added products that may generate an additional income. Unfortunately, nutrients and volatile solids are predominately in fine suspended particles that are not separated by available screen separators. We evaluated the use of polyarylamide (PAM) polymers to enhance separation of solids and nutrients from flushed swine manure with screens. Flush samples of varied strength (0.4 to 2.5% total solids) were obtained during a full pig growing cycle in a feeder-to-finish operation in North Carolina. Separation by screening alone was not effective, below 20% for solids and 10% for organic carbon. Flocculation treatment substantially increased separation of suspended and volatile solids (95%), oxygen-demanding compounds (69%), and also organic phosphorus (92%) and nitrogen (85%). We found that it was more economical to treat flushed manure with higher strength. Chemical cost for treatment of manure containing 2.5% solids was $1.27 per finished pig. Our results indicate that PAM flocculation can substantially increase capture of energy-yielding feedstock for energy production. The N:P nutrient ratio was also improved from 4.8 to 12.1 resulting in a more balanced effluent for crops. This indicates that with polymer enhanced solids separation the liquid effluent can be land applied at higher application rates without accumulating phosphorus in soil.

Technical Abstract: Most of the organic nutrients and oxygen-demanding compounds in liquid swine manure are contained in fine suspended particles that are not separated by available mechanical separators. Treatment with polyacrylamide (PAM) polymer prior to mechanical removal has the potential for enhancing solids-liquid separation, thus concentrating nitrogen (N), phosphorous (P) and organic C in the solids. In this work, we evaluated the effect of variation in manure strength typical of flushing systems on solids removal efficiency and chemical use efficiency. Flush samples of varied strength (0.4 to 2.5% total solids) were obtained during a full pig growing cycle in a feeder-to-finish operation in North Carolina. Separation by screening alone was not effective, <20% for suspended solids, <10% for COD and BOD, and <15% for N and P. Flocculation treatment substantially increased separation of suspended and volatile solids (95%), oxygen-demanding compounds (69%) and also organic P (92%) and N (85%). For every 100 g of TSS removed there was a 1.32 g reduction of COD, 3.32 g reduction of org. P, and 7.26 g. reduction of org. N. We found that it was more economical to treat flushed manure with higher strength. Therefore, reduction of water volume to clean the houses can result in significant savings (about 700%) in total polymer cost. Chemical cost for treatment of manure containing 2.5% solids was $1.27 per finished pig. The N:P nutrient ratio was also improved from 4.8 to 12.1 resulting in a more balanced effluent for crops. This indicates that with polymer enhanced solids separation the liquid effluent can be land applied at higher application rates without accumulating phosphorus in soil.

Last Modified: 4/18/2014